I know that there are plenty of specialty anti-fog products you can buy, but here's my list of homegrown anti goggle fog techniques I've used, know of others that have used or read about:
Take a bar of non-abraisive soap and soak it in a bit of hot water for a few minutes to soften it up (liquid soap works just as good). Once soft, scrape off a bit of the softened soap and put a light film of soap on the inside of the goggle lens. Once the film is dry, carefully buff the lens clear with a soft cloth. This is usually good for several hours of riding.
This technique must have been the brainchild of Idaho potato farmers, but it does work. Cut a slice off a spud and carefully rub the white part on the inner lense of the goggle. Like the soap technique, let the spud juice dry and buff the lense clear with a soft cloth. If you want, bake up the rest of the spud and eat it for dinner. I prefer lots of sour cream & bacon bits.
I read that skin divers use this technique, but in my experience, it will get you by in a pinch, but not as effective as others (doesn't last very long).
Wax On! Wax Off! Just about everyone has some of this stuff in their garage and it does work pretty well. Just make sure to use wax, not paint cleaners as they'll scratch your goggle lens.
You can purchase either a goggle that already has a dual pane lens, or get just the lens and replace your single goggle lens. I buy the basic scott 83 series goggles and then get the dual for it and swap. in really tough conditions ( all winter in the wet pacific northwest) I keep a "winter" goggle ready that has a dual pane lens AND some of the foam over the upper vents removed too. no need to worry about dust anyway.